Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!telebit!brian
From: brian@telebit.com (Brian Lloyd)
Newsgroups: comp.dcom.modems
Subject: Re: PPP and V.32bis/V.42bis (was Re: Uses of V.42 (bis?) data compression)
Keywords: PPP SLIP V.42bis
Message-ID: <1991Apr14.051825.16728@telebit.com>
Date: 14 Apr 91 05:18:25 GMT
References: <3908.280363d4@hayes.uucp> <1991Apr12.132116.11546@hobbit.gandalf.ca> <1991Apr13.070324.10288@wimsey.bc.ca>
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The Telebit NetBlazer is a dial-up IP router that uses SLIP or PPP as
a framing protocol.  We have spent quite a bit of time characterizing
the performance of SLIP and PPP with or without V.42 and V.42bis.

The previous posting indicated results that agree quite closely with
what we see both in our lab and in real life.  With a NetBlazer
driving a single T-1600 modem with traditional (no VJ header
compression) SLIP and the modems running V.42 and V.42bis I normally
see 1.5KB/s to 1.7KB/s throughput.  If the data is really compressible
I have seen performance as high as 2.6KB/s.  These are the values
reported by FTP so it is real-world throughput.

As a result of our experience, we have the NetBlazer configure the
modem for V.42 and V.42bis by default.  The latency is usually
acceptable for TELNET, rlogin, or other interactive activity (at least
it is for me and I am pretty picky).



-- 
Brian Lloyd, WB6RQN                              Telebit Corporation
Network Systems Architect                        1315 Chesapeake Terrace 
brian@napa.telebit.com                           Sunnyvale, CA 94089-1100
voice (408) 745-3103                             FAX (408) 734-3333